SCREENING, IDENTIFICATION AND CHARACTERISTICS OF YTTRIUM -RESISTANT BACTERIA IN THE RARE EARTH MINE TAILINGS OF SOUTHERN JIANGXI, CHINA

The pollution of rare earth elements in tailings soil is generally recognized, which is detrimental to the growth of organisms. An yttrium-resistant bacterium, Bl, was isolated from the soil in Longnan rare earth yttrium (Y) mining area, located in the Jiangxi Province of China. Polyphasic analysis, including a 16S rDNA phylogenetic tree as well as morphological and physicochemical properties, revealed that the isolate was a gramnegative, rod-shaped bacterium, which was recognized as Bacillus sp. Bl. Strain B1 is well known for its eosinophilic characteristics, while showing strong tolerance at pH 1.0, with its optimum growth pH value put at 4.0. In general, low concentrations of yttrium stress can promote the growth of the strain Bl. Hence, the growth of the strain B1 was significantly inhibited with an increasing concentration of yttrium stress. In fact, the strain B1 stopped growing when the yttrium concentration increased to 160 mmol/L with the pH of the solution at about 5. Acids can be used to influence the resistance of bacteria to yttrium. The more acidic the medium (low pH), the lower its tolerance to yttrium, with obvious dual stress effect. Research carried out on the tolerance characteristics of strain B1 to rare earth yttrium have also proven that the growth of the bacteria can reduce the yttrium content in solution. Also, that its tolerance to yttrium may have some correlation with the secretion of extracellular polymeric substances (EPS).